The present invention relates generally to dimmable lighting control systems. More particularly, the present invention relates to wireless controlled lighting systems having a shared signal path on output wires between a power stage and a load stage.
Light dimming is an effective way to achieve energy saving or energy management. Several popular dimming methods existing in the lighting market include but are not necessarily limited to: 0-10V analog dimming, step dimming, power line control, and DALI (“Digital Addressable Lighting Interface”) control. Each of these dimming methods require additional wiring for implementation of the respective control signals. This additional wiring makes retrofitting less attractive because wiring changes must be made to accommodate the dimming function.
Wireless control is very desirable, at least in part because the relevant control signals do not need any physical wiring configuration in order to reach the control unit. However, fluorescent ballasts or LED drivers are typically enclosed in a metal can, and are typically further enclosed in a metal lighting fixture. The respective metal housings may typically act like a signal shield that renders wireless communication impractical, if not nearly impossible.
For the purpose of making wireless lighting control practical, it would therefore be desirable that retrofitting such a control scheme would not require changes to existing LED driver or fluorescent lamp ballast wiring.
It would further be desirable that the wireless lighting control be implemented in such a way that the wireless signal receiving may be highly reliable.
Referring to FIG. 1, a wiring diagram as represented therein demonstrates a conventional configuration for a lighting system 10 including a fluorescent ballast or LED driver 12. As shown therein, a typical driver or ballast design includes an input of Vac mains 14 and two or more output leads 16 for providing power across a wiring arrangement 18 to input leads 20 associated with the load 22.
It would therefore be further desirable in view of such conventional configurations to use the output leads as a dimming/control signal feedback path to the ballast or driver, wherein no extra wiring or other wiring modifications would be needed to the ballast/driver in order to realize the dimming control function.